I would put it a little higher. Haven't seen an Erie 10 go for less than 50 unless it was cracked. So I would say at least 50.
An interesting thing about that skillet that I've wondered about...see that notch on the rib of the handle? I have an 8 that has that notch, and have seen quite a few other Erie's that have it...but not all do. I thought somebody did that to mine at some point, but now I think that happens at the foundry for some reason. Maybe from being mounted on the milling/grinding machine? I haven't seen this mentioned before, maybe it has, but quite a few Erie pans have that notch. Why do you think that is? :-?